Cirrus Logic CS485 Spécifications télécharger pdf (Page 159)

Linear Image Transforms

7-5

Discussion

The function iplRealFft2D() performs an FFT on each channel in the

specified rectangular ROI of the input image

srcImage

and writes the

Fourier coefficients in

RCPack2D format into the corresponding channel of

the output image

dstImage

. The output data will be clamped (saturated) to

the limits

Min and Max, which are determined by the data type of the output

image. For best results, use 32-bit data or, at least, 16-bit data.

Example 7-1 Computing the FFT of an Image

/*-------------------------------------------------

; Matlab example

» rand('seed',12345); x=round(rand(4,4)*10), fft2(x)

89 10-7i -9 10+7i

-1 + 6i 8 -21i 13 + 2i -8 - 3i

-3 10+1i 3 10-1i

-1 - 6i -8 + 3i 13 - 2i 8 +21i

// Result of iplRealFft2D function:

89 10 -7 -9

-1 8 -21 13

61012

-3 -8 3 3

--------------------------------------------------*/

int example71( void ) {

IplImage *imga, *imgb; int i;

const int src[16] = {

9, 7, 4, 1, 7, 5, 1, 7,

6, 6, 1, 9, 3, 10, 9, 4};

__try {

imga = iplCreateImageHeader(

1, 0, IPL_DEPTH_8U, "GRAY", "GRAY",

IPL_DATA_ORDER_PIXEL, IPL_ORIGIN_TL,

IPL_ALIGN_DWORD, 4, 4, NULL, NULL,

NULL, NULL);

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Cirrus Logic CS485 Spécifications Page 159